Search

Multisubstituted furans occupy a pivotal position within the realms of synthetic chemistry and pharmacological science due to their distinctive chemical configurations and inherent properties. We herein introduce a tandem difunctionalization protocol of alcohols for the efficient synthesis of multisubstituted 2,3-dihydrofurans and γ-butyrolactones through the combination of photocatalysis and iron catalysis under mild conditions. Photoredox alcohol α-C(sp3)–H activation and Pinner-type intramolecular cyclization are two key processes. This method features significant convenience, economic benefits, and environmental friendliness.

In this article, an adaptive boundary control strategy of a rigid–flexible robot with concurrence failures and multiple constraints is studied based on a distributed parameter model. The complex dynamic of the rigid–flexible robot system is expressed by ordinary differential equation (ODE) and partial differential equation (PDE), which can avoid control overflow problem. The multifault concurrent cases of joint torque and force actuator failures as well as angular velocity and vibration displacement sensor failures are considered. An adaptive fault-tolerant control for flexible–rigid robot is presented to compensate the effects of actuator and sensor failures. Then, the tangent barrier Lyapunov function (BLF) and the integral BLF are designed to ensure multiple output states within their constraints. The finite-dimensional boundary controller consisting of measurable sensor signals can achieve position tracking and vibration suppression. The closed-loop system of the asymptotic stability is proved by using the extended LaSalle’s invariance principle. According to the comparative simulations, the effectiveness of the presented controller is verified.

Interpretable policy distillation aims to imitate a deep reinforcement learning (DRL) policy into a self-explainable model. However, the distilled policy usually does not generalize well to complex tasks. To investigate this phenomenon, we examine the experience pools of DRL tasks and find that these interactive experience distributions are heavy tailed. However, this critical issue is largely ignored by existing approaches, and, thus, they do not fully unitize the less frequent but very critical experience points. To address this issue, we propose characterizing decision boundaries via the minimum experience retention to deal with the heavy-tailed experience distributions. Our method identifies critical experience points that are close to the model’s decision boundaries, and such experience points are more critical because they portray the prerequisite of a model to take an action. As a result, our method distills the DRL policy to a self-explainable structure without a neural structure and ambiguous intermediate parameters. Through experiments on six games, we show that our method outperforms the state-of-the-art baselines in cumulative rewards, stability, and faithfulness.

This paper concerns an infinite-dimensional observer for manipulation of flexible beam by a rigid arm robot. The complex dynamic of the system is described by distributed parameter model in terms of ordinary differential equations and partial differential equation. A novel infinite-dimensional observer is proposed to estimate the vibration information of the flexible object. In addition, an observer-based independent joint controller is designed to achieve the position control and vibration suppression, which do not need end-point boundary control. The semigroup theory and LaSalle’s invariance principle are adopted to prove the asymptotic stability of the robot system. The efficiency of the observers and the proposed control strategy are demonstrated by numerical simulations.

Here we report facile and manipulable access to methylenebisamide derivatives via visible-light-driven radical cascade processes incorporating C(sp3)–H activation and C–N/N–O cleavage. Mechanistic studies reveal that a traditional Ir-catalyzed photoredox pathway and a novel copper-induced complex-photolysis pathway are both involved, contributing to activating the inert N-methoxyamides and rendering the valuable bisamides. This approach exhibits many advantages, including mild reaction conditions, broad scope and functional group tolerance, and competitive step economy. Given the mechanistic plenitude and operational simplicity, we believe this package deal paves a promising way for the synthesis of valuable nitrogen-containing molecules.

In this study, we aim to enhance the efficiency and performance of vortex tubes by identifying the optimal material for their manufacture under specific conditions using computational fluid dynamics (CFD) simulations. We first establish a theoretical model of vortex tubes and propose a dynamic partition modeling method. Through theoretical analysis, we demonstrate the superiority of metallic materials in vortex tube applications, particularly regarding their energy distribution efficiency. We then conduct CFD simulations and experimental validations to systematically analyze the performance of vortex tubes made from different materials. The simulations utilize compressed air as the working fluid, with inlet pressures ranging from 0.1 MPa to 0.5 MPa. The materials considered include Copper, Aluminum, Steel, PVC, and Wood. Throughout the simulations, the cold mass fraction is maintained at 0.1, and the length-to-diameter ratio (L/D) of the vortex tube is set at 16. Using the standard k-ε model, steady-state numerical simulations of the gas flow inside the vortex tube are performed to analyze the variations in velocity, pressure, and temperature for different materials, pressures, and roughness conditions. Based on the physical properties of the materials, we find that metallic materials, particularly Copper, exhibit higher temperature gradients compared to non-metallic materials, with the order being Copper > Aluminum > Steel > PVC > Wood.

Naked oat grain is easily contaminated by microorganisms, and it needs pretreatment to extend its shelf life. Low‐temperature plasma treatment (LTPT) has the advantages of less energy consumption, safety, and convenience, and its applications in grain include microbial inactivation and flour modification. Therefore, we studied the changes in oat microbes and the physicochemical properties of oats at different plasma treatment times (0, 5, 10, 15, and 20 min at an output discharge voltage of 60 kV). The results demonstrated that LTPT significantly decreased the number of microorganisms with the increase in treatment time, especially at 20 min. LTPT increased the L* and b* values and decreased the a* value of oat flour. Proper treatment time (5–10 min) did not affect the germination rate of the grain. Compared to the control sample, LTPT increased the water‐binding capacity and swelling power of flour and decreased the peak viscosity, final viscosity, and setback value. However, LTPT did not change the crystal structure. Besides, by fitting the peak of the amide region in Fourier transfer infrared analysis, it was found that the β‐sheet and α‐helix increased after treatment for 5–10 min. These results indicated that LTPT (20 min) can effectively reduce the microbial count of oats and proper time treatment (5–10 min) can regulate the function of the flour and improve its quality. LTPT as a new nonheat treatment technology can not only effectively reduce the microbial content of the grain but also improve the quality of the flour, which is a better pretreatment method for oat flour.

AbstractThe Chinese Super League (CSL) has witnessed unprecedented growth in recent years via evolutions in Chinese football clubs’ business models and the league environment. This paper analyses business model innovation (BMI) in the light of changing ecosystem factors via a case study of the Guangzhou Evergrande Taobao FC. It analyses the types of BMI and finds that BMI constancy and novelty are key to the club’s success. The study identifies policy and investors as the two ecosystem factors with the most significant influence on the club’s BMI. We argue that CSL clubs have unique and under-rated value capture structures, where the value is captured by their investors rather than by the clubs themselves. Being sensitive to the ecosystem is another key factor and we give guidance on how to anticipate ecosystem changes and adjust business models accordingly. This can be generalized to other organizations and industries.

Surgical site infections, defined as acute wound infections requiring surgical intervention within 90 days post-surgery, were retrospectively compared between a novel, zipper-like closure method (ZM) and staples in 682 patients (904 knees) and 772 patients (971 knees), respectively. The incidence of deep infections was 0.6% for staples and 0.2% for ZM (p = 0.169) and superficial infections was 0.1% for staples and 0.0% for ZM (p = 0.518). With no difference in wound complications, the ZM may be preferred since the two-week post-operative clinic visit required for wound check and staple removal was eliminated, thereby, decreasing clinic volume.

CO2 enhanced gas recovery (CO2-EGR) is a promising, environment-friendly technology with simultaneously sequestering CO2. The goals of this paper are to conduct simulations of CO2-EGR in both homogeneous and heterogeneous reservoirs to evaluate effects of gravity and reservoir heterogeneity, and to determine optimal CO2 injection time and injection rate for achieving better natural gas recovery by employing a genetic algorithm integrated with TOUGH2. The results show that gravity segregation retards upward migration of CO2 and promotes horizontal displacement efficiency, and the layers with low permeability in heterogeneous reservoir hinder the upward migration of CO2. The optimal injection time is determined as the depleted stage, and the corresponding injection rate is optimized. The optimal recovery factors are 62.83 % and 64.75 % in the homogeneous and heterogeneous reservoirs (804.76 m × 804.76 m × 45.72 m), enhancing production by 22.32 × 103 and 23.00 × 103 t of natural gas and storing 75.60 × 103 and 72.40 × 103 t CO2 with storage efficiencies of 70.55 % and 67.56 %, respectively. The cost/benefit analysis show that economic income of about 8.67 and 8.95 million USD can be obtained by CO2-EGR with optimized injection parameters respectively. This work could assist in determining optimal injection strategy and economic benefits for industrial scale gas reservoirs.

We report the synthesis and photophysical characterization of a triplet donor–acceptor dyad (3), which was constructed from a quinoidal naphthalene thioamide triplet sensitizer 1and a perylene derivative 2as the acceptor. The dyad of interest exhibits convoluted photophysical characteristics from the donor and acceptor chromophores. The kinetic analysis of the phosphorescence of 3produced two lifetimes τ1= 1.1 ms and τ2= 20 ms. The shorter component was attributed to the phosphorescence lifetime of the sensitizer 3(1)* moiety (within the dyad) and the longer lifetime can be assigned to either the triplet state of the acceptor 3(2)* or a charge transfer (CT)* species. This result was further corroborated with time-resolved transient absorption studies which revealed the CT band in the transient spectrum of the dyad. In this picture, the 1···2interactions, which led to the formation of the CT species, was found to be the dominant photodynamics. Alternatively, dyad 3was used to sensitize free perylene acceptor; the bimolecular 3(3)* → perylene triplet energy transfer allowed triplet–triplet annihilation based photon upconversion to generate anti-Stokes photoluminescence of perylene using a 532 nm excitation source.

Four studies investigate whether gay Asian Americans are stereotyped as more American than Asian Americans who are presumed straight. Gay Asian American men (Study 1) and women (Study 2) were rated as more American than their counterparts whose sexual orientation was unspecified. However, sexual orientation did not influence judgments of Whites’ American identity. The relationship between Asian Americans’ sexual orientation and perceptions of their American identity was mediated by a belief that American culture is relatively more accepting of gay people than Asian culture (Studies 3 and 4). Manipulating how accepting of gay people a target’s country of origin is relative to the United States altered ratings of American identity for gay but not straight targets (Study 4). Using an intersectional approach, these studies demonstrate that sexual orientation information comes together with race to influence who is likely to be perceived as American.

Depending on the intrinsic photoactivity of nitroarenes, we herein developed a practical Brønsted acid-catalyzed decarbonylative amide synthesis from alkynes and photoexcited nitroarenes without any metal or photocatalyst. This method exhibited compatibility with water and air, broad substrate applicability, marvelous functional group tolerance, and wide applications in scale-up synthesis, late-stage functionalization, and total synthesis. Mechanism studies and DFT calculations supported that a 1,3,2-dioxazole intermediate was involved, and gaseous carbon monoxide was the only byproduct during amide construction.

Owing to their remarkable practicality and utility, phosphonium salts have attracted substantial interest and are widely applied in critical areas, such as medicine, materials science, and catalysis. Herein, we developed a facile and photocatalyst/metal-free synthetic strategy for the preparation of phosphonium salts utilizing aryl halides/arylthianthrenium salts as aryl radical precursors. This approach is disclosed to undergo an efficient light-induced electron donor–acceptor pathway, facilitating the synthesis of a structurally diverse range of phosphonium salts.

Thiophosphates serve as pivotal reagents within the realms of both organic and inorganic synthesis, with their most notable applications observed in agricultural chemistry. This manuscript delineates a modular three-component synthetic strategy for site-selective arene C–H thiophosphorylation with thianthrenium salt, 1,4-diazabicyclo[2.2.2]octane-sulfur dioxide (DABSO), and diarylphosphine oxides as substrates. This approach facilitates the metal-free and green synthesis of a diverse spectrum of S-aryl phosphorothioates through C–H functionalization and late-stage modification showcasing practicality and broad applicability.

In-depth theoretical analysis of the consequences of methylation of the rim sites of corannulene is completed. The full set of derivatives ranging from parent C20H10to fully substituted C20(CH3)10has been evaluated, revealing consistent trends along the series. The controlled one-electron chemical reduction of selected methylated corannulenes, such as monomethyl- (C20H9(CH3)), sym-pentamethyl- (1,3,5,7,9-C20H5(CH3)5), and decamethylcorannulene (C20(CH3)10) has also been investigated. Cesium metal was used as a reducing agent to access endo complexes having cesium ion placed inside the concave cavity of the monoreduced bowls. Two products, [{Cs+(18-crown-6)}{C20H9(CH3)−}] (1) and [{Cs+(18-crown-6)}{C20H5(CH3)5–}] (2), have been crystallized in the presence of 18-crown-6 ether and crystallographically characterized to confirm the concave cesium ion coordination. The direct structural comparison of 1and 2with the complex of unsubstituted corannulene, [{Cs+(18-crown-6)}{C20H10–}] (3), has been conducted. Furthermore, the nature and strength of metal binding for the series of concave cesium complexes with methyl-substituted corannulene bowls has been evaluated using different theoretical methods.

Accurate density data and a predictive equation of state (EoS) for the CO2–CH4system are significantly important for the application of natural gas purification and carbon capture, utilization, and storage (CCUS). In this work, densities of the CO2–CH4binary system with CO2mole fractions ranging from 0.0998 to 0.8988 were measured at temperatures of 313–353 K and pressures of 3–18 MPa using a magnetic suspension balance, and the compressibility factors and the relative combined standard uncertainties were also calculated correspondingly. The PC-SAFT EoS was employed for the density modeling, and the PR EoS was used for comparison. The measured density data in this work and experimental density data from the literature were used to optimize the binary interaction parameter kijin the PC-SAFT EoS and PR EoS. The predicting abilities of PC-SAFT and PR EoS with the optimized kijwere compared to the case without binary interaction (kij= 0). The PC-SAFT EoS with the optimized kijhad better performance than the PR EoS with optimized kij, and it could predict the density properties of the CO2–CH4system accurately, with an average absolute deviation (AAD) of 1.16%. Modelings from PC-SAFT with and without the optimized kijwere then compared with the measured densities obtained in this work. The relative deviations for the calculation from PC-SAFT with the optimized kijwere within the range from −3.93 to 2.94%. Moreover, the CO2–CH4binary systems with CO2mole fractions of 0.7985 and 0.8988 in this work can be regarded as CO2-rich fluids, and their density reductions compared with pure CO2were evaluated for the measured density data and the values calculated from the modified PC-SAFT.

A combination of advanced sequencing and mapping techniques is used to produce a reference genome of Aegilops tauschii, progenitor of the wheat D genome, providing a valuable resource for comparative genetic studies.

CO2storage in saline aquifers is considered a potential solution for CO2mitigation, owing to its significant capacity and worldwide distribution capability. It is therefore becoming more important to understand the underground CO2/brine flow mechanisms. CO2migration is primarily controlled by the pore‐scale subsurface flows in different saline aquifer sites with variable reservoir formation compositions and reservoir conditions. Variations occur in the state of CO2phase (gas versus supercritical), brine salinity, and rock wettability, under different reservoir conditions, and may result in different subsurface CO2/brine migration phenomena. In this study, we investigate the drainage and imbibition procedures of CO2and brine by injecting fluids into unconsolidated sand packs under different conditions of CO2phase states, brine salinity, and wettability of sand packs. The pore‐scale fluid distribution is visualized using micro X‐ray computed tomography (micro‐CT). It is found that the phase states of CO2, brine salinity, and wettability have low impacts on CO2distribution during drainage. However, the increase in brine salinity significantly damages the connectedness of the water phase in pore structures and further decreases the CO2‐brine interfacial areas. In addition, a pore‐scale event called the droplet fragmentation of nonwetting phase is found to occur in the imbibition procedure, which is considered to be beneficial to the dissolution trapping in CO2geological storages. It is experimentally demonstrated that the pore structure of rock cores is a factor that significantly contributes to droplet fragmentation. Connectedness of water phase weakens with increase in the water salinitySalinity and wettability result in different CO2‐brine interfacial propertiesPore space with a large aspect ratio and long pore‐throat is advantageous for CO2droplet fragmentation

Herein, we report the development of the photocatalytic C–H functionalization of methane, ethane, and heavier gaseous alkanes with good yields and selectivity, broad scope (57 examples), mild conditions, and low cost. Kinetics and density functional theory calculations were investigated for the key photoinduced ligand-to-metal charge transfer and hydrogen atom transfer processes to reveal the detailed mechanism of iron photocatalysis. This work may bring novel ideas for feedstock upgrading and catalyst design.

Although carbon monoxide (CO) has been known to bind to the ferrous heme in cytochrome P450 enzymes (P450s) since the earliest days of P450 research, details on the nature of the ferrous–CO bonding remain elusive. This study employed dispersion-corrected density functional theory (DFT) calculations and DFT-based theoretical analyses to investigate the complexes between CO and a thiolate- or imidazole-ligated heme that contains ferric or ferrous iron. Traditionally, the ferrous–CO bonding in heme systems has been interpreted qualitatively in terms of σ donation and π backdonation. Complementary occupied-virtual orbital pair (COVP) analysis yielded one orbital pair for σ donation and two for π backdonation together with the specific magnitude of their energetic contributions. The charge-transfer effect for these three orbital pairs has nearly the same energetic significance in the ferrous–CO complexes. Therefore, in total, the π-backdonation effect is much greater than the σ-donation effect. In contrast, the σ-donation effect is more significant in the ferric–CO complex because of the less efficient π backdonation. The nature of ferric–CO and ferrous–CO bonding was further scrutinized using the generalized Kohn–Sham energy decomposition analysis (GKS-EDA) scheme, whose results highlighted the significance of various effects in enhancing the Fe–CO bonding for the thiolate- and imidazole-ligated heme groups. In particular, the intrinsic repulsion effect plays a crucial role in promoting the preferential binding of CO toward the ferrous heme and in determining the geometry of the complexes.

Two‐component polymer solutions [i.e., poly(methacrylic acid) (PMAA) and poly(vinylpyrrolidone) (PVP)] were prepared through solution polymerization. The complex system PMAA/PVP was obtained through the mixing of a PMAA solution and a PVP solution in different volume ratios at certain concentrations. The properties of the component solutions and the complex system were investigated with transmittance, surface tension, and viscosity measurements. The results showed that the properties of the complex system were related not only to the ratio of PMAA to PVP but also to the concentration of the PMAA and PVP solutions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2280–2286, 2005